[dragonsky]

Where older and more venerable people being vaccinated early? They still are more likely to die if infected. Then a spread of vaccination to the general population. You would have to look at a breakdown of who was vaccinated at the time you saw the lower vaccine benefit.

[sgtnoodle]

I thought about that, but it seems like whatever changed must have happened nearly instantaneously. Looking at the plot, it's a rather pronounced step change.